adv7189b Analog Devices, Inc., adv7189b Datasheet - Page 35

• Manufacturer Part Number: adv7189b
• Description: Multiformat Sdtv Video Decoder
• Manufacturer: Analog Devices, Inc.

DNR_TH[7:0] DNR Noise Threshold, Address 0x50[7:0]
The DNR_TH[7:0] value is an unsigned 8-bit number used to
determine the maximum edge that is interpreted as noise and
therefore blanked from the luma data. Programming a large
value into DNR_TH[7:0] causes the DNR block to interpret
even large transients as noise and remove them. The effect on
the video data is, therefore, more visible.
Programming a small value causes only small transients to be
seen as noise and to be removed.
The recommended DNR_TH[7:0] setting for A/V inputs is
0x04, and the recommended DNR_TH[7:0] setting for tuner
inputs is 0x0A.
The default value for DNR_TH[7:0] is 0x08, indicating the
threshold for maximum luma edges to be interpreted as noise.
COMB FILTERS
The comb filters of the ADV7189B have been greatly improved
to automatically handle video of all types, standards, and levels
of quality. The NTSC and PAL configuration registers allow the
user to customize comb filter operation, depending on which
video standard is detected (by autodetection) or selected (by
manual programming). In addition to the bits listed in this
section, there are some further ADI internal controls; contact
ADI sales for more information.
Rev. B | Page 35 of 104
NTSC Comb Filter Settings
Used for NTSC-M/J CVBS inputs.
NSFSEL[1:0] Split Filter Selection NTSC, Address
0x19[3:2]
The NSFSEL[1:0] control selects how much of the overall signal
bandwidth is fed to the combs. A narrow split filter selection
gives better performance on diagonal lines, but leaves more dot
crawl in the final output image. The opposite is true for selecting
a wide bandwidth split filter.
Table 44. NSFSEL Function
NSFSEL[1:0]
00 (default)
01
10
11
CTAPSN[1:0] Chroma Comb Taps NTSC, Address
0x38[7:6]
Table 45. CTAPSN Function
CTAPSN[1:0]
00
01
10 (default)
11
Do not use.
NTSC chroma comb adapts 3 lines (3 taps) to
2 lines (2 taps).
NTSC chroma comb adapts 5 lines (5 taps) to
3 lines (3 taps).
NTSC chroma comb adapts 5 lines (5 taps) to
4 lines (4 taps).
Description
Description
Narrow
Medium
Medium
Wide
ADV7189B